中科大源：

deb http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-backports main multiverse restricted universe
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-proposed main multiverse restricted universe
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-security main multiverse restricted universe
deb http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-updates main multiverse restricted universe
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic main multiverse restricted universe
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-backports main multiverse restricted universe
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-proposed main multiverse restricted universe
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-security main multiverse restricted universe
deb-src http://mirrors.ustc.edu.cn/ubuntu-ports/ bionic-updates main multiverse restricted universe

清华源：

deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic main multiverse restricted universe 
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic-security main multiverse restricted universe 
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic-updates main multiverse restricted universe 
deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic-backports main multiverse restricted universe 
deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic main multiverse restricted universe 
deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic-security main multiverse restricted universe 
deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic-updates main multiverse restricted universe 
deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports/ bionic-backports main multiverse restricted universe